The variability of orchid population size

Gillman, Michael P. and Dodd, M. E. (1998) The variability of orchid population size. Botanical Journal of the Linnean Society, 126 (1-2). pp. 65-74. ISSN 0024-4074

Full content URL:

Full text not available from this repository.

Item Type:Article
Item Status:Live Archive


Orchid population size has long been believed to be highly variable in time and space. Here we present the first quantitative assessment of the variability of orchid population sizes and compare them with plant and animal population data from the literature. Three measures of temporal variation were used (standard deviation of log10 (population size), Hurst exponent and variance in the intrinsic rate of increase). Eight unfertilized plots of Orchis morio in a factorial fertilizer experiment were assessed for variability in population size over a 26 year period. The Hurst exponent across the eight plots gave measures consistent with pink noise well into black noise (0.86 to 1.87). The variation in the intrinsic rate of increase suggested that the expected time to extinction in the plots differed by an order of magnitude. Standard deviation of log10 (population size) across plots was greater than the corresponding temporal variation within plots. Standard deviation of log10 (population size) reached an asymptote between 10 and 20 years. The range of temporal variation between plots in this and other orchid populations was as great as the mean values reported for birds, insects and mammals. These results have highlighted the importance of spatial variation: until we know the relative importance of spatial and temporal variation for more plant species we will be unable to assess whether orchid populations are more variable in size than other species.

Additional Information:Article first published online: 28 June 2008
Keywords:green-veined orchid, population size, spatial variation, temporal variation, Orchis morio
Subjects:C Biological Sciences > C180 Ecology
C Biological Sciences > C200 Botany
Divisions:College of Science > School of Life Sciences
Related URLs:
ID Code:15519
Deposited On:20 Oct 2014 11:05

Repository Staff Only: item control page